Protein of the week- EASTER

Since it isn’t very long until Easter I had a look at an interesting protein named EASTER.

Of course EASTER was discovered in Drosophila melanogaster. It is a maternal gene translated in the developing embryo, where it cleaves proSPAETZLE to activate SPAETZLE, which in turn establishes the dorsoventral axis of the embryo. EASTER is just the last step in a tightly regulated cascade of cleavage events, necessary for developing a perfect fly. It is translated as a protoenzyme, which needs to be activated by cleavage through the protease SNAKE. (1)

Most of the time EASTER is in a complex with a protease inhibitor that stops SNAKE, but in the ventral part of the embryo, EASTER gets activated and in turn activates SPAETZLE. SPAETZLE activates the TOLL receptor, which after a signaling cascade results in the expression of DORSAL and a concentration gradient that defines the up- and down side of the embryo.

EASTER was first described in 1984, the paper was published in September, but it is very possible that this protein was first discovered during the Easter holidays and similar to the Easter islands, just named for the time of year.

What I also found pretty interesting about EASTER is its involvement in pattern formation on butterfly wings. So Happy Easter.




Misra S, Hecht P, Maeda R, Anderson KV. Positive and negative regulation of Easter, a member of the serine protease family that controls dorsal-ventral patterning in the Drosophila embryo. Development. 1998 Apr;125(7):1261-7.

Steward R. Relocalization of the dorsal protein from the cytoplasm to the nucleus correlates with its function. Cell. 1989 Dec 22;59(6):1179-88.

Rebecca Chasan, Kathryn V. Anderson The role of easter, an apparent serine protease, in organizing the dorsal-ventral pattern of the Drosophila embryo Cell 1989, 56(3) 391–400

Anderson KV, Nüsslein-Volhard C. Information for the dorsal–ventral pattern of the Drosophila embryo is stored as maternal mRNA. Nature. 1984 Sep 20-26;311(5983):223-7.

Post a Comment

Your email address is never shared. Required fields are marked *